I got inspired yesterday after reading that thread, and disassembled a 20L leaker with sentimental value. The bottom trim came right off, in fact, giving me a reason to pursue a rebuild rather than simply going over the inside seams with new sealant.
How to put this...
The bottom pane wasn't actually the bottom of the tank. Remove the trim, and the thing was resting on the sides/back. Normal maybe, but I doubt anyone has run into one where the bottom was 1" off the surface. Mmmmboy. Even better, they'd apparently used the bottom frame as a crutch and hadn't gotten sealant all the way down on one corner. No biggie you say? Seeing as how the bottom wasn't all the way at the bottom anyway? Well, the gap extended to just above the bottom. If they hadn't made such a mess of the interior seal by glopping it everywhere, the tank would never have held water.
Most of the seams were easy to get a utility knife in. Only one was tight.
What can I say? I was a dumb teenager and too fascinated by this odd tank size to look closer.
My mind is aglow with trancient nodes of thought, careening through a cosmic vapor of invention - Hedley Lamar